The invention concerns a method for temperature compensation of an analog, temperature dependent differential signal of a pressure measuring circuit, in particular for measuring pressure by means of a piezoresistive pressure transducer wherein a measurement bridge is disposed on a pressure measurement cell to provide a differential output signal which can be fed to a differential amplifier for generation of a pressure measurement signal. An associated measuring circuit is provided which is arranged to provide an indicated reading as a multiple of either the measurement bridge signal or the signal from the differential amplifier.
Piezoresistive pressure transducers have been known for a long time and have proven themselves in practice. They are applied both when measuring for absolute pressures and for reference measurements. Here, the pressure transducers available on the market consist of a pressure cell on whose pressure measuring diaphragm there is provided, as an example, a bridge circuit made up of resistances for measuring pressure.
In practice, however, posed is the problem that the resistance values of the resistances in the bridge circuit are temperature dependent, hence dependent upon the pressure sensor, and, accordingly, the output pressure measurement signal from the measurement bridge also changes with the temperature. Because of this, an exact pressure measurement is not possible.
It has already been proposed to connect an analog compensation circuit on the output side of the measuring bridge in order to obtain a pressure measurement signal less dependent upon temperature. However, these circuits are, in practice, expensive and also do not provide the desired results relative to an exact measurement of pressure.
Furthermore, it has also been made known measuring circuits wherein the analog pressure measurement signal is digitalized and then entered into a downstream computer or calculator. With the aid of the calculator, the digitalized measurement signal is then processed according to computations such that temperature compensation of the measured signal takes place. This method and its associated arrangement, however, also display several disadvantages. For one thing, resolution of the pressure measurement signal is considerably reduced since the entire measured signal must first be digitalized. In doing this, the resolution can correspond maximally only to the individual digital steps. Additionally, the required hardware, in the form of a required calculator or computer, is enormously comprehensive and particularly expensive, so that this method and this arrangement in many cases already precludes, right from the start, an exact pressure measurement.